1. Field of the Invention
The present invention relates to a method, system, and an article of manufacture for consistent copying of storage volumes.
2. Description of the Related Art
Information technology systems, including storage systems, may need protection from site disasters or outages, where outages may be planned or unplanned. Furthermore, information technology systems may require features for data migration, data backup, or data duplication. Implementations for disaster or outage recovery, data migration, data backup, and data duplication may include mirroring or copying of data in storage systems. Such mirroring or copying of data may involve interactions among servers, clients, storage systems and networking components of the information technology system.
Enterprise storage servers (ESS), such as, the IBM* TotalStorage Enterprise Storage Server*, may be a disk storage server that includes one or more processors coupled to storage devices, including high capacity scalable storage devices, Redundant Array of Independent Disks (RAID), etc. The enterprise storage servers are connected to a network and include features for copying data in storage systems. *IBM, IBM TotalStorage Enterprise Storage Server, Enterprise System Connection (ESCON) are trademarks of International Business Machines Corp.
Enterprise storage servers (ESS) may include copy functions for copying data either locally, i.e., within the same on-site ESS, or remotely, i.e., copying data to a separate remote-site ESS. The copy functions can be classified as either dynamic or point-in-time copy functions. Dynamic copy functions constantly update the secondary copy as applications make changes to the primary data source. Point-in-time copying techniques provide an instantaneous copy or view of what the original data looked like at a specific point in time.
In certain enterprise storage servers there may be copy functions, such as, Flashcopy, that provide a point-in-time copy of the data. Implementations may copy data between a set of local/source volumes and a corresponding set of remote/target volumes in enterprise storage servers. Flashcopy may provide a point-in-time copy for ESS volumes by creating a physical point-in-time copy of the data, with minimal interruption to applications, and make it possible to access both the source and target copies substantially immediately. Both the source and the target volumes reside on the same ESS system, although implementations may be possible where the source and target volumes reside on different ESS systems. Further details of the Flashcopy are described in the IBM publication “IBM TotalStorage Enterprise Storage Server: Implementing ESS Copy Services with IBM eServer zSeries,” IBM document no. SG24-5680-01 (Copyright IBM, 2003), which publication is incorporated herein by reference in its entirety.